Electric heating



Aug. 27, 1935. R. H. PARK ELEQTRIC HEATING Filed Dec. 12, 1931 5Sheets-Sheet 1 I Mari Aug. 27, 1935. I R. H. PARK 2,012,618

ELECTRIC HEATING L Filed Dad. 12; 19s1-- 5 Sheets-Sheet z 2 ,6 446- /7 52111;111:111 EiQIIIIIQQl I112i}; (Q2 E 5 gm T x m mix '@lm@fl@ m l@ 5 I6/ "A" 1 Wu lnvezafiav:

Aug. 27,1935 R. H. PARK 2,012,613

I ELECTRIC HEATING Filed Dem-12, 19:51 5 Sheets-Shee t 4 u 27, 1935'; R.H. PARK 2,012,618

ELECTRIC HEATING Filed Dec. 12, 1931 5 Sheets-Sheet 5 Patented Aug. 27,1935 UNITED STATES PATENT OFFICE 14 Claims.

This invention relates to electric heating, and the. object is toprovide an improved mechanism wherein the object to be heated,forexample, a

" liquidecontaining vessel, is included as a part of a 6 circuit of highamperage and low voltage.

My invention will be well understood by reference to the followingdescription of the specific embodiment thereof shown by way of examplein the accompanying drawings, wherein:-

Fig. l is a plan view of a stove such as would be used for domesticcooking purposes;

Fig. 2 is a section through the top of the stove and the vessel thereontaken on the line 2- -2 of Fig. 1 and showingyparts beneath inelevation;

Fig. 3 is a similanview of the parts shown in Fig. 2 asseen from theleft of that figure.

Fig. 4 shows certain parts of Fig. 2 dissociated fromadjacent'mechanism;

Fig. 5 is a detailed section on an enlarged scale on theline 5-'5 ofFig. 3;

Fig. 6 is a section on the line 66 of Fig. 3;

Fig. 7 is a section on an enlarged scale on the line |l of Fig. 6; and

Fig. 8 is a wiring diagram.

Electric heating appliances for cooking purposes are commonly usedwherein the heat is derived from a resistance wire heated toincandescence.

, While such heating elements are satisfactory for baking, broiling andthe like, they are slow and uneconomical for such operations as boiling,and in' the construction about to be described (see Fig. 8) a liquidcontaining vessel 9, such as a saucepan, is included as a part of acircuit ii of high amperage and low voltage which may be the secondarycircuit of the transformer ll, of which they primary coils l5 may beenergized from a source of relatively high voltage, such, for example,as

the ordinary 110 volt electric lighting mains. A

current of high heating capacity is thus passed directly through thepan, heating the liquid therein rapidly and efilciently. To excludecurrent from the contents of the pan with possible electrolytic actionthereon I prefer to provide the pan with an enamel lining It. The bottomof the saucepan 9 may be provided with downwardly projecting, prong-likecontacts '|'I which may be firmly engaged by clamping jaws I8 (see Fig.2) to connect the pan in the circuit.

Means, preferably power means, are utilized to close the clamps and,after they are closed, to initiate the current supply. When the heatingoperationis completed, thesupply circuit is preferably opened and thenthe clamps are released. I will first describe the operation in ageneral way with reference to the diagram, Fig. 8, and then,

with reference to the other figures, the mechanical construction hereinshown-by way of example. Referring, therefore, to Fig. 8, the pan 9being placed in position with the contacts between the open jaws I! ofthe clamps to permit the latter to be closed thereon, theheatingoperation may be started by moving the double pole switch 2| to the leftin the figure to engage the contact 23. Current is thus supplied throughwire 24 and bridge 25 to an electric motor 21 which by mechanical means(not shown in the diagram) closes the clamps l9. When the clamps areclosed, movement of the motor initiates the flow of ourrent to thetransformer i3, and herein a cam 29 driven by the motor closes switch 3|energizing the solenoid II. The core of this solenoid rising causesbridge I! to close the circuit to the primary II of the transformer. Italso lifts bridge 25, breaking the circuit to motor 21, stopping thesame, and lifts bridge 31 in the conductor leading to,a motor magnet 39so that the latter cannot receive current while the solenoid isenergized. The number of turns in the primary and consequentiy the rateof heating may be controlled in the usual manner by a controlling switch4|.

When the heating is completed, switch 2| is moved over into contact withthe pole 43. By this means the circuit of solenoid 33 is broken andbridge 3! falls, interrupting the current to the primary ll. As. bridge31 closes, current fiows through pole 43 to the motor magnet 39, theoperation of which provides by means hereinafter to be described for therelease of clamps l9 and also for the reopening of switch 3|.

Referringnow to Fig. 2, the contacts are there shown as passing throughsuitable openings 45 (see Fig. l) in the stove top 41 beneath whichopenings the clamping jaws IO are arranged. These jaws may take the formshown in Fig. 5 and may comprise suitable contact blocks 49 mountedbetween side members 5| pivotally mounted on rock shafts 53 andyieldably connected thereto by means of the strong torsional sprlhgs 55which yield when the blocks are pressed against the contacts H. Theblock 9 may be laterally extended as shown in Fig. 3 to provide forconnection of the flexible conductor 51 thereto. The side surface of theblock 49 makes the electric contact and I preferably provide aninsulating covering 59 over the top face of the law to avoid anypossible inefficient closing of the circuit by engagement of the bottomsof the contacts II with the tops of the jaws.

Referring to Fig. 2. the rock shafts 53 for the pairs of contacts arepreferably intergeared by pinions as shown whereby on turning of oneshaft the pairs of clamping jaws will open and links 61 forming a togglewhich carries at its central pivot a cam follower 69. Movement of thisfollower upwardly to the position shown in Fig. 2 will cause the clampsto close. The toggle is herein straightened by the cam 1| on cam shaft13 driven at suitable speed from motor 21 already referred to in thedescription of the wiring diagram. It will be seen that if the cam 1| isturned from the position shown in Fig. 2, it will engage the follower 69and gradually raise it to the point there shown, but when the nose ofthe cam passed the follower, if no other mechanism is provided thefollower would be free to fall and the clamps would be opened andreleased on each revolution of the cam shaft. I therefore provide amember 15, best shown in Fig. 4, having the portion 11 of substantiallythe same radius as the highest portion of the cam and yieldablyconnected to the cam 1| by means of spring 19 which normally tends tohold the member 15 rotated clockwise from the position of Fig. 4 withits stop shoulder 8| in contact with pin 83 projecting from the cam andwith the part 11 in alignment with the highest or nose portion of thecam. The member 15 is also-provided with a projecting pin 85 adapted toengage a lug 81 on a pivoted arm 89 normally held by means of spring 9|in the position shown in Fig. 4 with lug 81 in the path of pin 85 butwhich may be depressed by means of the motor magnet 39, as willhereinafter be described. In the operation of the parts, therefore, whenthe high part of the. cam, the member 15 moving therewith, brings thetoggle to the position shown in Fig. 2, pin 85 makes contact with stop81 and stops further movement of the member 15, the cam, however,continuing to move and tensioning spring '19. The part 11, therefore,remains stationary under the follower 69 and holds the clamps closedeven after the nose of the cam 1| passes beyond the follower to theposition shown in Fig. 2.

Camshaft 13 may also be provided with a tappet or cam 93 adapted, whenthe parts reach the position shown in Fig. 2, to operate a snap switch3| which may be of the type shown in the patent to De Reamer 1,579,082,March 30, 1926, and. unnecessary to illustrate or describe in detail.This switch is here shown as carried on a pivoted arm connected by rod91 to crank arm 6|. Thus,

8) solenoid 33, initiating the flow of current to the heating elementand by the lifting of bridge 25 breakingthe circuit to the motor so thatthe cam shaft 13 stops in the position shown. When the heating iscompleted, if the switch 2| is moved to the off position in contact withpole 43, the circuit of the solenoid 33 is broken as before described.The core of solenoid 33 falls and the bridge 35 breaks the circuit tothe primary l5 of the transformer. The circuit of motor magnet 39 isclosed at 43 and 31, the magnet attracts its armature, pulling down arm89, releasing the member 15 to spring 19 so that the surface 11 is drawnout from beneath the cam follower, re-

leasing the rock shaft to the action of spring 63 (Fig. 2) and openingthe clamps. In this opening movement arm 95 swings downwardly, removingswitch 3| from the nose of cam 93 and permitting the same to snap open.This action, while a rapid one, permitting the cooking vessel to beimmediately removed, is nevertheless clelayed until after the heatingcircuit is broken since motor magnet 39 cannot be energized until bridge31 is closed and bridge 35 opened on deenergizing of the solenoid 33.The possibility of arcing is thus avoided.

Referring again to Fig. 8, I have there shown means to open the heatingcircuit in case the resistance abnormally rises, as might happen, forinstance, when a boiling operation was in question and the pan boileddry and became red hot. For this purpose I interpose in the circuit ofsolenoid 33 a safety switch which may comprise a fixed contact 99 withwhich cooperates a spring blade |8| connected in the circuit by means ofa flexible lead I03 and carried by a rocking beam I05 pivoted at I01 andhaving the spring I09 attached thereto through a suitable lever arm asshown so as to hold the beam tilted either in the closed position of theswitch as shown or in the open position when the beam has rockedsomewhat clockwise.- A handle III on the beam provides for returning theswitch to the closed position shown after it has been opened in themanner about to be described. Opposite ends of the beam are here shownas connected to the cores of coils H3 and H5 respectively, the conjointaction of which on their respective cores controls the position of thebeam. Coil H3 is arranged in series in the circuit of the primary coilsl5 of the transformer and is so wound as to attract its core with aforce proportional to the current (amperage). Coil H5, however, is ofhigh resistance and may be bridged across a portion of the coil l5,conveniently with the addition of a resistor H1, and .acts on its corewith a force proportional to the electro-motiveforce or voltageConsequently when the resistance of pan 9 rises, the current demand ofthe secondwhen the toggle formed by arm 61 is moved tQ- ary falls,current (amperage) in primary l5 deward the position of Fig. 2 to closethe clamp arm 6| consequently is swung clockwise and arm 95 is liftedcam 93. I

It will .thus be seen that when switch 2| is moved onto the contact 23and the motor 21 energiz'ed, cam 1| starts to turn. When it has reacheda position about 35 short of that shown in Fig. 2, the highest point ofthe cam has acted on follower 69-and closed the clamps which are held inthatposition'by the action of the surface 11 as described. Meanwhileswitch 3| has been brought into the path of the cam 93, and when the camshaft reaches the positionshown in Fig. 2, that switch is thrown,energizing (see Fig.

to bring the switch into the path of creases, the electro-motive forceincreases, and the force of coil H5 overcomes the forceof coil H3,rocking beam I95 clockwise andopening the switch.

It will be seen that the safety switch 99-|0|. the operation of whichhas just been described,

' is disposed in the lead from pole 23 of switch 2| before conductor 24branches therefrom and stove its positioning with the contacts l1presented to openings 45 is'facilitated. The flange H9 is preferablymade discontinuous, as shown in Fig. 6, preferably being broken atdiametrically opposite points and-the groove is likewise broken (seeFigs. 6 and '7) by means of projec- ,t ions I23 adapted to be receivedin the discontinuities of the flange. The notch in the flange and thesides of this rib 'may similarly be bevelled to facilitate positioning.It will be understood that these notches and ribs facilitate the angularpositioning of the pan so that the contacts l1 may easily bepassed'through the openings it. These guiding parts are situated at theexterior easily visible and do away with any need of fumbling in placinthe pan in position.

In the case of a domestic heating stove, such as shown in Fig. 1,besides the usual baking oven and broiler at I28 I may provide.stations, herein the two shown at the bottom of the figure, constructedasdescrlbed for boiling or like operations involving the heating ofrelatively large quantities of material, and also stations such as thoseshown at the rear of the flgure with resistance heating elements I21 ofcustomary type adapted to be heated by the ordinary current. I prefer toarrange these heating elements in such manner that openings 45a andgrooves .lIla

similar to theopenings l5 and grooves III are provided in the stove top.This permits utensils primarily adapted for use for boiling purposes onthe stations in front to be placed on or used in connection with theother heating elements. It will be understood that the openings a are ormay be dummies with no mechanism such as that shown in Fig. 2 beneaththem.

I am aware that the invention may be embodied in other specific formswithout departing from the spirit or essential attributes thereof, and Itherefore desire the present embodiment to be considered in all respectsas illustrative and not restrictive; reference being had to the appendedclaims rather than to the foregoing description to indicate the scope ofthe invention.

I claim:

1. An electric heating device comprising a line having clamps forengaging contacts on a device to be heated to include the same in anelectric circuit, means to supply current of high amperage and lowvoltage to said line, a manually operable controlling switch, a motorand a relay having circuits passing through one pole of the switch, asecond switch in the relay circuit, mechanical means operated by themotor for closmg the clamps, means operated by the motor for closing thesecond switch, a second motor having aoircuit passing through anotherpole of the controlling switch, means operated by said second motor forreleasing the clamps, switches operated by said relay for the currentsupply to the heater and for the circuits of said motors, the latterbeing open when the flrst is closed and vice versa. 1

2. In an electric heating device of the kind described, intergeared rockshafts carrying clamping jaws to engage contacts on a vessel, an arm onone of the shafts and a cam to act on the arm to close the jaws.

3. In an electric heating device of the kind described, inter-gearedrock shafts carrying clamping jaws to engage contacts on a vessel, anarm on 'one of the shafts, a switch for controlling the supply ofcurrent to said clamp, a cam shafthavingbothacamtoactonsaidarm and a camcontrolling said switch.

4. In an electric heating device of the class described, intergearedrock shafts carrying clamp jaws, means for normally rotating the same torelease the clamps, an arm for rotating the same to close the clamps, acam for swinging said arm, a support for said arm spring-connected tosaid cam, and a releasable stop for said support.

5. In a device of the class described, intergeared rock shafts carryingclamp jaws, means for normally rotating the same to release the clamps,an arm for rotating the same to close the clamps, a cam shaft having acam for swinging the arm, a support for said arm free on the shaft butspring-connected to said cam, a switchoperating cam on the shaft, aswitch, a movable support for the. switch connected to the jaws andmoving into the path of said latter cam when the jaws close, and areleasable stop for said support.

6. In a device of the kind described, in combination withcontact-engaging clamps, means normally tending to open the same, an armfor closing the same, a cam for swinging said arm, a support for saidarm spring-connected to said cam, and a releasable stop for saidsupport.

'7. In a device of the kind described, in combination with thecontact-engaging clamps, means normally tending to open the same, an

arm for closing the same, a cam shaft having a cam for swinging the arm,a support for said arm free on the shaft but spring-connected to saidcam, a switch-operating cam on the shaft, a switch, a movable supportfor the switch connected to the jaws and moving into the path of saidlatter cam when the jaws close and a releasable stop for said support.

8. An electric heating device comprising a line having clamps forengaging contacts on a device to be heated to include the same in anelectric circuit-means to supply current of high amperage and lowvoltage to said line, said clamps being normally open when the line isdead whereby said contacts may be freely positioned between the samewithout impediment, power means for closing the clamps, energy-storingmeans operated by said power means, and means to release the clamps tothe action of said energystoring means for rapidly separating the same.

9. Equipment for electric cooking comprising a self-contained portablevessel adapted to receive material to be heated and having studsprojecting exteriorly therefrom, electric heating means incorporated inthe vessel for which heating means said studs constitute terminals, asupport for the vessel, pairs of relatively movable clamp jawspositioned adjacent the support and connected respectively to oppositesides of a source of electric energy whereby when the pairs are closedon the studs respectively the said heating means forms a part of acircuit extending from one pair to another, said jaws having an openposition wherein by a mere movement of superposition ofthe vessel on thesupp rt they freely receive the studs between them with clearancebetween'the parts, and means for closing and opening the jaws and forenergizing and deenergizing the circuit interrelated to exclude' priorto opening of the jaws, the closing of the jaws and the deenergizationof the circuit being initiated by separate manual operations.

10. Equipment for electric cooking comprising a self-contained portablevessel adapted to receive material to be heated and having studsprojecting exteriorly therefrom, electric heating means incorporated inthe vessel for which heating means said studs constitute terminals, asupport for the vessel, pairs of relatively movable clamp jawspositioned adjacent the support and connected respectively to oppositesides 01' a source of electric energy whereby when the pairs are closedon the studs respectively the said heating means forms a part of acircuit extending from one pair to another, said jaws having an openposition wherein by a mere movement of superposition of the vessel onthe support they freely receive the studs between them with clearancebetween the parts, and means responsive to a manually efiected operationfor closing the jaws and eiiective only after such closure to permitenergization of said circuit and means responsive to an independentmanual operation for deenergi'zing the circuit and eifective only aftersuch deenergization to permit opening oi the jaws.

11. Equipment for electric cooking comprising a self-contained portablevessel adapted to receive material to be heated and having studsprojecting exteriorly therefrom, electric heating means incorporated inthe vessel for which heating means said studs constitute terminals, 9.support for the vessel, pairs of relatively movable clamp jawspositioned adjacent the support and connected respectively to oppositesides of a source of electric energy whereby when the pairs are closedon the studs respectively the said heating means forms a part of acircuit extending from one pair to another, said jaws having an openposition wherein by a mere movement 01' superposition of the vessel onthe support they freely receive the studs between them with clearancebetween the parts, and means responsive to independent manual operationsrespectively ior sequentially closing the jaws and energizing thecircuit, and for sequentially deenergizing the circuit and opening thejaws.

12. Equipment for electric cooking comprising a self-contained portablevessel adaptedto receive material to be heated and having studsprojecting downwardly therefrom, electric heating means incorporated inthe vessel for which heating means said studs constitute terminals, asupport for the vessel having openings or relatively large size freelyto pass the studs, pairs of relatively movable clamp jaws beneath theopenings and connected respectively to opposite sides of a source ofelectric energy whereby when the pairs are closed on the studsrespectively the said heating means forms a part of a circuit extendingfrom one pair to another, said jaws having an open position wherein by amere movement of superposition of the vessel on the support they ireelyreceive the studs between them with clearance between the parts, andmeans responsive to independent manual operations respectively forsequentially closing the jaws and energizing the circuit, and forsequentially deenergizing the circuit and opening the jaws.

13. Equipment for electric heating comprising a self-contained portablevessel adapted to receive material to be heated and having studsprojecting downwardly from its bottom, electric heating meansincorporated in the vessel for which heating means said studs constituteterminals, a support for the vessel, pairs of relatively movable clampjaws positioned adjacent the support and connected respectively toopposite sides of a source of electric energy whereby when the pairs areclosed on the studs respectively the said heating means forms a part ofa circuit extending from one pair to another, said jaws having an openposition wherein by a mere movement of superposition of the vessel onthe support they freely receive the studs between them with clearancebetween the parts, cooperating means on the support and vesselrespectively for centering and orienting the vessel on said support tofacilitate insertion of the studs between the open jaws and manuallyoperable means for closing the jaws and energizing the circuit and alsofor deenergizing the circuit and opening the jaws. 14. An electricheating device comprising a line having clamps for engaging contacts ona device to be heated to include the same in an electric circuit, meanstosupply current of high amperage and low voltage to said line, andmeans mutually exclusive in their operation foropening and closing theclamps.

. ROBERT H. PARK.

